1. Field of the Invention
The present invention relates to web slitting apparatus, and more particularly, to web driven slitting apparatus for use in conjunction with winding apparatus such as for paper and the like where the web is to be slit lengthwise during winding.
2. Prior Art
Web driven slitters are well known, such as for example the type disclosed in U.S. Pat. No. 3,685,379. They are often used with winding apparatus in which a web of material such as paper or the like is intended to be slit lengthwise during the winding procedure so that the web material can be wound into separate rolls of lesser width than the web material being slit. Such web driven slitters provide a smooth and accurate cut in the web once the web is brought up to its normal line speed.
However, such devices suffer from a common deficiency in that when the winding operation of the web material is initially begun, i.e. during the transient phase between initial threading of the web on to the spindle of the winding machine and the time at which the web is brought up to line speed, such slitters generally do not attain the same peripheral edge speed as the speed of the web, thus often resulting in tearing of the web. This produces a portion of the web which is unsatisfactory for subsequent use. Also, when the web is first fed through such web driven slitters, it may not initially be cut at all since the cutting capability of some of the devices is dependent upon the velocity of rotation of the cutters and the line speed of the web. In such cases, it then becomes necessary for the operator of the winding apparatus to slit the web by some other means, which also usually results in substantial waste of material until the winding apparatus is up to speed.